New gene plays key role in colon cancer Hopkins professor leads researchers who found gene tied to cancer onset

March 15, 1991|By Los Angeles Times

A multinational group of researchers headed by a Johns Hopkins oncology professor has discovered a gene that plays a key role in the development of colon cancer, opening the way for tests to identify high-risk individuals and for early detection of the disease.

The discovery, being reported in today's edition of the journal Science, may also lead to the development of new therapies for colon cancer, which is the second most common form of cancer in the United States. Last year, it struck 155,000 people and killed 61,000.

"This is a very significant finding," said molecular biologist Robert Weinberg of the Massachusetts Institute of Technology. "This could represent the first entree we have into understanding why many families have high rates of colon carcinoma."

The new discovery is the most recent development in the explosive growth of the field of cancer genetics. To date, researchers have identified at least five dozen genes that are linked to the onset of malignancy in humans.

But the tentatively identified gene -- which is also involved in the development of colon polyps -- is one of the most exciting so far, experts said, because colon cancer is so widespread and because the gene plays such a key role in the onset of the disease. Many believe that developing the ability to overcome the effects of the new gene, called MCC (for Mutated in Colon Cancer), could halt colon cancer in its tracks.

The team found MCC on the so-called long arm of chromosome 5, one of the 46 chromosomes that carry the genetic blueprint of a human.

Much research over the past decade had shown that a defect in a specific region of chromosome 5 is found in at least 50 percent of colon tumors. MCC, the researchers report, is most likely the single gene within that region that suffers the damage.

Bert Vogelstein, oncology professor at Johns Hopkins University, one of the lead authors of the report, and his colleagues believe MCC causes the inherited disease familial adenomatous polyposis, commonly called FAP. Members of FAP families are born with a genetic defect in MCC that produces large numbers of benign polyps, or growths, in their colons.

These polyps often go on to become tumors, although FAP is believed to account for only a small fraction of colon cancers, perhaps 1 percent. But previous research had suggested that damage to the same gene occurs in the bulk of those colon cancers that seemingly strike the population at random.